1. Field of the Invention
This invention relates to a spool structure around which a belt-shaped object, such as an image-receiving sheet used for sublimation printing, is wound.
2. Description of the Related Art
FIG. 6 is a perspective view of a conventional spool structure.
The conventional spool structure 20 has a core 21, a first flange 22 and a second flange 23.
An image-receiving sheet, which is used for sublimation printing, is adapted to be wound around the core 21. The core 21 has a positioning groove 21a at a first end portion 21-1 on the side of the first flange 22, and a positioning groove 21d at a second end portion 21-2 on the side of the second flange 23. The core 21 also has through holes 21e and 21f appearing at an outside surface thereof, on which the image-receiving sheet is wound.
The first flange 22 has: a jaw part 22c that can protect and guide the image-receiving sheet wound around the core 21; a gear part 22b that can transmit a driving force from a printing apparatus not shown; a shaft part 22a; and a fitting part 22d that can be fitted with the core 21. The jaw part 22c, the gear part 22b, the shaft part 22a and the fitting part 22d are integrally formed.
The second flange 23 has: a jaw part 23c that can protect and guide the image-receiving sheet wound around the core 21, similarly to the jaw part 22c; a shaft part 23a; and a fitting part 23d that can be fitted with the core 21. The jaw part 23c, the shaft part 23a and the fitting part 23d are integrally formed.
The fitting part 22d has an outside diameter suitable for fitting with the inside diameter of the core 21. A positioning projection (not shown) is formed at a location corresponding to the positioning groove 21a. 
Similarly, the fitting part 23d has an outside diameter suitable for fitting with the inside diameter of the core 21. A positioning projection 23f is formed at a location corresponding to the positioning groove 21d. 
The first and second flanges 22 and 23 have nail parts 22g and 23g, respectively. The nail parts 22g and 23g are adapted to engage with the holes 21e and 21f provided in the core 21 by using their own elasticity, respectively. Thus, the first and second flanges 22 and 23 are adapted to be surely fixed to the core 21 not to come off the core 21.
In the conventional spool structure 20, the through holes 21e and 21f appear on the surface of the core 21 on which the image-receiving sheet is wound. Thus, there is a problem that the shapes of the holes 21e and 21f may be transferred to the image-receiving sheet and may remain therein.
As the image-receiving sheet, a polypropylene foam film or a polyethylene terephthalate foam film, which are superior in cushioning performance and thermal-insulating performance, are used in order to uniformly and efficiently transfer dye to a receiving layer by means of a pressing contact with a thermal head. In the case, the shapes of the holes 21e and 21f may be transferred more easily, for example the shapes of the holes 21e and 21f may be transferred even to (and may remain in) an outermost part of the wound image-receiving sheet.
In addition, a surface for sublimation printing is a glossy surface. Thus, if the shapes of the through holes 21e and 21f remain in the image-receiving sheet, the shapes (traces) are very conspicuous, so that quality as printed matter may be deteriorated.
When the first and second flanges 22 and 23 are removed from the core 21, the nail parts 22g and 23g have to be pressed via the through holes 21e and 21f. Thus, it is necessary for the through holes 21e and 21f to pass through the surface of the core 21 for winding the image-receiving sheet. In other words, if the through holes 21e and 21f are buried, the first and second flanges 22 and 23 can not be removed from the core 21.
Therefore, the object of this invention is to provide a spool structure wherein it is unnecessary to provide an unevenness pattern or a hole appearing on an outside surface of a core, on which an image-receiving sheet or the like is wound, and wherein a flange can be surely combined normally and easily removed if necessary.
The invention is a spool structure including: a cylindrical core having a smooth outer surface, and an inner surface with a engaging part; and a flange having a jaw part that can be arranged at a side end of the core, and a nail part that can engage with the engaging part of the inner surface of the core.
According to the invention, since the engaging part is provided on the inner surface of the core, the outer surface of the core can be completely smooth.
For example, the engaging part consists of a concavity having a bottom surface.
In addition, for example, the nail part consists of an elastic member that is urged toward the engaging part of the inner surface of the core so as to engage with the engaging part, and the nail part is adapted to be released from the engaging part when a predetermined releasing force is acted so as to move the nail part away from the engaging part.
In the case, preferably, the jaw part has a through hole that allows an access from an area opposite to the core with respect to the jaw part to a surface of the nail part on a side of the engaging part. Thus, by using a jig such as a bar or a stick, the predetermined releasing force may be given to the nail part more easily so as to move the nail part away from the engaging part.
In addition, in the case, preferably, the nail part extends from a side end of the core to the engaging part along the inner surface of the core, the nail part has a tip part that can engage with the engaging part, the core has a groove at an area in the inner surface facing the surface of the nail part on the side of the engaging part, and the groove of the core can communicate with the through hole of the jaw part. Thus, the predetermined releasing force may be given to the nail part further more easily so as to move the nail part away from the engaging part.
More preferably, the nail part has a inclined surface rising toward the tip part at a root-side-adjacent portion adjacent to the tip part, and the inclined surface can be contained in the groove of the core. Thus, by causing an external force in a direction of the rotation axis of the core to act on the inclined surface by using a jig such as a bar or a stick, the predetermined releasing force may be given to the nail part more easily to move the nail part away from the engaging part.
Alternatively, this invention is a spool structure including: a cylindrical core having a smooth outer surface, and an inner surface with a first engaging part and a second engaging part; and a flange having a jaw part that can be arranged at a side end of the core, a first nail part that can engage with the first engaging part of the inner surface of the core, and a second nail part that can engage with the second engaging part of the inner surface of the core.
According to the invention, since the plurality of engaging parts are provided on the inner surface of the core, the outer surface of the core can be completely smooth, and the core and the flange can be connected more surely.
For example, each of the first and second engaging parts consists of a concavity having a bottom surface.
In addition, for example, the first nail part consists of an elastic member that is urged toward the first engaging part of the inner surface of the core so as to engage with the first engaging part, the first nail part is adapted to be released from the first engaging part when a first predetermined releasing force is acted so as to move the first nail part away from the first engaging part, the second nail part consists of an elastic member that is urged toward the second engaging part of the inner surface of the core so as to engage with the second engaging part, and the second nail part is adapted to be released from the second engaging part when a second predetermined releasing force is acted so as to move the second nail part away from the second engaging part.
In the case, preferably, the jaw part has a first through hole that allows an access from an area opposite to the core with respect to the jaw part to a surface of the first nail part on a side of the first engaging part and a second through hole that allows an access from the area opposite to the core with respect to the jaw part to a surface of the second nail part on a side of the second engaging part.
In addition, in the case, preferably, the first nail part extends from a side end of the core to the first engaging part along the inner surface of the core, the first nail part has a first tip part that can engage with the first engaging part, the second nail part extends from a side end of the core to the second engaging part along the inner surface of the core, the second nail part has a second tip part that can engage with the second engaging part, the core has a first groove at a first area in the inner surface facing the surface of the first nail part on the side of the first engaging part and a second groove at a second area in the inner surface facing the surface of the second nail part on the side of the second engaging part, the first groove of the core can communicate with the first through hole of the jaw part, and the second groove of the core can communicate with the second through hole of the jaw part.
More preferably, the first nail part has a first inclined surface rising toward the first tip part at a first root-side-adjacent portion adjacent to the first tip part, the first inclined surface can be contained in the first groove of the core, the second nail part has a second inclined surface rising toward the second tip part at a second root-side-adjacent portion adjacent to the second tip part, and the second inclined surface can be contained in the second groove of the core.
Preferably, the flange consists of one integrally molded resin member.
For example, an image-receiving sheet used for sublimation printing is adapted to be wound around the outer surface of the core. Even in the case, a shape of an unevenness pattern or a hole is never transferred to the image-receiving sheet, so that beautiful printed matter can be obtained.